Lots of reasons that have to do with delicacy, bamboo, attention and eyesight
Imagine a weaver sitting at a loom. Even though it is hard back-breaking work, they have several tools to help them. Not so the jamdani weaver. This is a difficult weave for many reasons, says Kolkata-based doyenne of textiles, Ruby Palchoudhuri.
Free form designs
First of all, the designs are free form in a way. A graph is placed under the threads. That’s it. The weaver has to count the number of threads to lift for the additional (supplementary) weft that is woven into the design. It is free form mixed with mathematical precision.
If it is a multi-coloured flower, then the weaver has to keep track of multiple colours at multiple locations, count the threads that are needed to be lifted, add the supplementary weft thread using a bamboo stick, a tamarind piece or a thick needle.
High Count Cotton
They have to make sure the delicate high-count cotton threads don’t break. The supplementary weft is so delicate that it seems to float within the saree. Coarser thread will cause the designs to rise above the surface. So you see, the skill is in the memory, the counting, the care, the meticulous keeping track of details (which colour goes where and how much thread to cut and use for which section). This is a technique that is learned over decades.
This is why the jamdani is special.
Below are some scholarly accounts with citations.
“Jamdani weaving is labour intensive, requiring a delicate touch. Seated atthe loom, the master and his assistant weave patterns with colour or metal thread,once guided by designs on paper but now by verbal instructions. The jamdani work is essentially tapestry work, the wefts forming the pattern where needed, being threaded through the warps with a wooden or bamboo needle. By using thread as fine as the compound weaves, the weft patterns seem to merge and float within the cloth, rather than appear as an overlay or woven decoration.” Parul Bhatnagar in a paper about jamdani
Extinct cotton variety
“The creation of muslin tested the skill, patience and creativity of all the stakeholders: farmers, dyers, spinners and weavers on the loom. The renowned mulmul khas was made from the cotton plant called Neglecta (known in Bengali as Phuti Karpas), that used to grow abundantly along the mud-lined banks of the Brahmaputra river. The mythical plant could make mulmul khas of thread count of above a thousand. Thread count refers to the number of horizontal(warp) and vertical threads (weft) per square inch: the higher the thread count, the softer the fabric. The mulmul khus needed not only the right fibre but also sharp eyes and nimble fingers of young girls who had to sit in humid conditions with a spindle or takua (often on the river banks or on a moored boat in the early mornings or late afternoon) to wind and prepare the yarn.” Shruthi Issac Jamdani: The Legacy of the Woven Winds.
“Bundles of thread are dyed in a variety of colors. The dyed thread is strengthened and softened by soaking overnight in a solution of rice water starch, allowing the woman to wind it more easily onto bobbins. this tedious work is done early in the morning, usually between four and nine, before the increasing heat dries the thread, making it more difficult to handle. The wound bobbins are sent to another worker who prepares the warp on a beam. Afterwards, the warp is sent to the weaver’s house where it is set upon a loom. Drawings are placed under the warp as a guide. The weaver, almost always a man, may or may not follow the drawing, often preferring to work from intuition alone. Coloured threads are carefully inserted and hand tied into the fine weft to create patterns on the plain weave.” Sourav Das. Approach in contemporizing jamdani: the extra-weft insertion technique.